AU2013261858B2

AU2013261858B2 - Kit and method for producing a radiopharmaceutical

Info

Publication number: AU2013261858B2
Application number: AU2013261858A
Authority: AU
Inventors: Dirk Muller
Original assignee: Zentralklinik Bad Berka GmbH
Current assignee: Zentralklinik Bad Berka GmbH
Priority date: 2012-05-18
Filing date: 2013-05-14
Publication date: 2016-08-04
Anticipated expiration: 2033-05-14
Also published as: EA201401273A1; AU2013261858A1; US9421283B2; KR20150010742A; JP2015516457A; BR112014028611A2; HK1201479A1; IL235643A0; CA2873711A1; EP2849807B1; WO2013171188A1; US20150133634A1; IL235643A; DE102012208375B4; PL2849807T3; CN104321084A; EP2849807A1; DE102012208375A1; IN2014DN10403A

Abstract

The invention relates to a kit (1) for producing a radiopharmaceutical (8), comprising: a cation exchange cartridge (2); a reaction vial (3) having a marker precursor; a solution vial (4) having a solvent; = an elution vial (5) having a sterile solution comprising common salt (NaCl) and hydrochloric acid (HCl); and a buffer salt. The invention further relates to a method for producing a radiopharmaceutical (8).

Description

Kit and method for producing a radiopharmaceutical

The invention relates to a kit and to a method for producing a radiopharmaceutical.

Imaging techniques for medical diagnosis are commonplace, and in some cases have been so for decades. In some of these techniques, examples being positron emission spectroscopy (PET) or single photon emission computer tomography (SPECT), peptides, as for example edotreotide (DOTATOC), are labeled with radionuclides, as for example 68gallium, and used as radiopharmaceuticals, also called tracers. Within the human body, the radiopharmaceutical binds to particular receptors, which especially in the case of tumor cells are overexpressed. By means of the imaging techniques, the elevated beta-plus decay of the 68gallium can be ascertained and localized. According to [I. Velikyan: Synthesis, Characterisation and Application of 68Ga-labelled Macromolecules. Dissertation, Uppsala University, 2005], the 68gallium isotope decays with a half-life of 67.629 minutes to an extent of 89% with emission of a positron with at most 1.9 MeV, and to an extent of 11% with electron capture; the product in each case is the stable isotope 68zinc. In nuclear medicine application, the positron which has been emitted collides with an electron after a few millimeters, with which it breaks down to form two photons each with 511 keV, the two photons being irradiated from the annihilation site at an angle of virtually 180° from one another. The irradiated photons can be detected with appropriate detectors, and the location of the annihilation can be determined very precisely by reconstruction of a plurality of detection events .

In view of the short half-life of 68gallium, the radiopharmaceutical cannot be held for a prolonged time, but must instead be prepared a relatively short time prior to the intended use. 68Gallium is generated by what are called gallium-68 generators, also called 68Ge/68Ga generators, from 68germanium. 68Germanium has a half-life of 270.8 days and decays into 68gallium. This accumulates in the generator to a concentration governed by its own decay. The 68gallium formed is separated from the stationary phase of the 68germanium mother nuclide by means of a solvent which is introduced into the generator and with which only gallium, but not germanium, is eluted.

In known methods, hydrochloric acid with a normality of 0.05 N to 0.4 N is used for the eluting. The elution volume in this case is between 5 ml and 10 ml. The eluate, accordingly, contains hydrochloric acid and cannot be used directly to label peptides. A variety of solutions have been disclosed for this problem.

In the case of the method of anionic concentration, the eluate is admixed with a large volume of concentrated hydrochloric acid, the 68Ga is collected by means of an anion exchanger, and it is then eluted with water into a HEPES buffer solution (2-(4-(2-hydroxyethyl)- 1-piperazinyl)ethanesulfonic acid) for the labeling of, for example, peptides. With this method, subsequent purification of the product is required, in other words the removal of unwanted substances. Moreover, large quantities of hydrochloric acid must be used.

Also known is combined cationic/anionic concentration, in which case two different cartridges are used for the cation exchange (SCX - strong cation exchanger) and for the anion exchange (SAX - strong anion exchanger).

With the cationic concentration method, the 68gallium is held on a cation exchanger (SCX) and then eluted with an acetone/hydrochloric acid solution. The product obtained therefore comprises acetone, which, prior to use in the human body, must be removed by distillation at temperatures above 90°C. In order to verify complete removal of the acetone, intensive quality control is required, by means of a gas chromatograph, for example.

It is an object of a preferred embodiment of the invention to specify a kit for the improved production of a radiopharmaceutical, and also to specify a corresponding improved method.

The object is achieved in accordance with the invention by a kit of the invention and by a method of the invention.

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

Advantageous embodiments of the invention are subject matter of the dependent claims.

According to a first aspect of the invention there is provided a kit when used for preparing a radiopharmaceutical from a 68Ge/68Ga generator eluate, comprising: a cation exchange cartridge for holding the generator eluate, a reaction vial with a ligand-conjungated peptide, a solution vial with a solvent comprising an aqueous solution of acetic acid and hydrochloric acid, an elution vial with a solution comprising sodium chloride and hydrochloric acid, a buffer salt, and instructions to add the solution to the solution vial and to elute through the cartridge into the reaction vial,

According to a second aspect of the invention there is provided a method for preparing a radiopharmaceutical, comprising the steps: eluting of a 68Ge/68Ga generator using hydrochloric acid as an eluant for obtaining a generator eluate comprising 68Gallium, feeding the generator eluate through a cation exchange cartridge, which collects the 68Gallium, and separates the 68Gallium from the used eluent, eluting the collected 68Gallium from the cation exchange cartridge using a solution comprising sodium chloride and hydrochloric acid, and feeding the resulting eluate, into an aqueous precursor mixture comprising at least a ligand-conjugated peptide thereby forming a reaction solution, and wherein the solution for eluting the collected 68Gallium from the cation exchange cartridge follows directly after the generator eluate is fed through the cation exchange cartridge. A vial may also be termed an ampoule or septum bottle.

The buffer salt may be present, for example, in the reaction vial or in the solution vial.

The contents of the reaction vial have preferably been lyophilized.

Additionally provided in the reaction vial may be lyophilized ascorbic acid or another suitable stabilizer. The stabilizer prevents radiolytic degradation of the labeled substance during the use of the radiopharmaceutical.

As buffer salt, for example, ammonium acetate or sodium acetate may be used.

The kit is used as follows: A 68Ge/68Ga generator provides the 68gallium needed for labeling. The 68Ge/68Ga generator is eluted using hydrochloric acid, with a concentration of 0.1 mol/1, for example. In this way, 68gallium is eluted. The generator eluate is supplied to the SCX cartridge. The SCX cartridge used may be, for example, a silica gel-based (silica based) cartridge. The SCX cartridge is preconditioned, for example, with 1 ml of hydrochloric acid of 5.5 mol/1 concentration, and 10 ml of water. The preferably lyophilized mixture in the reaction vial is dissolved with the solvent from the solution vial. The SCX cartridge is then eluted, using the solution from the elution vial, into the reaction vial.

The reaction solution which is produced in the reaction vial may optionally be heated at 90°C to 100°C, over a time of 5 minutes to 15 minutes, for example, more particularly seven minutes, in order to accelerate the reaction, in which the 68gallium joins with the labeling precursor to form the tracer. The reaction may also take place at room temperature, in which case a correspondingly greater amount of time may be needed.

The concentration of unbound 68gallium is preferably smaller than 5%. The radiochemical purity of the tracer is greater than 95%. The reaction mixture contains no toxic or objectionable substances, and so there is no need for subsequent purification. After sterile filtration, carried out optionally, the radiochemical yield is around 82% (n.d.c. - non decay corrected).

At the end of the reaction, the radiopharmaceutical may be neutralized by addition of a sterile phosphate buffer, an example being 2 ml of sodium phosphate, 1 mmol/ml Na+, 0.6 mmol/ml PCq3-, pH 7.0.

Quality control by thin-layer chromatography may then follow. The tracer thus produced can be used subsequently, without further purification, as a radiopharmaceutical.

The kit of the invention can be used for routinely available application in clinical practice in the context of 68Ga labeling procedures. The kit of the invention reduces the level of operation with concentrated hydrochloric acid during the purifying and concentrating procedure on the 68Ga eluate. The attainable end product (tracer) is available with high purity and in a high yield of around 80% to 95%. As a result, it is likewise possible to avoid the use of acetone or other organic solvents or compounds such as 2-(4-(2-hydroxyethyl)- 1-piperazinyl)ethanesulfonic acid (HEPES). In this way, there is also no need, relative to methods known from the prior art, for verification that the acetone has been removed completely, and so there is no requirement for intensive quality control, by means of a gas chromatograph, for example. In this way, it is made possible to produce kits which can be employed by medical staff in a relatively simple way, by adding the solution to the lyophilized mixture, without any need for costly and complicated laboratory equipment.

The tracers obtained are stable for longer than tracers known from the prior art, allowing multi-dose products to be produced for the labeling and investigation of a number of patients.

In one embodiment of the invention, the reaction vial contains a lyophilized mixture of sodium acetate and a ligand-conjugated peptide, as for example DOTA- (1,4,7,10-tetraazacyclododecane-1,4,7, 10-tetraacetic acid) or NODAGA-conjugated peptide, more particularly DOTATOC (edotreotide) or DOTATATE (DOTA-[Tyr3 ] octreotate) . The tracer thus formed can be used in particular for the diagnosis of neuroendocrine tumors by means of positron emission tomography.

Instead of sodium acetate, ammonium acetate may be used in principle, but sodium acetate is more suitable for lyophilization.

In one embodiment of the invention, the reaction vial contains : at most 1 mg, preferably 15 pg to 100 pg, of the conjugated peptide, 20 mg to 40 mg, preferably 27.6 mg, of buffer salt, more particularly sodium acetate, at most 100 mg, preferably at most 5 mg, of L-ascorbic acid.

In one embodiment of the invention, the solution vial contains : 1 ml to 10 ml of water and also hydrochloric acid and acetic acid in an amount such that the pH of the solution composed of the contents of the reaction vial, the solvent from the solution vial, and the elution vial solution used to elute the SCX cartridge is between 3 and 4.

In one embodiment of the invention, the solution vial contains : 1 ml to 10 ml, preferably 1 ml to 3 ml, of water 2 μΐ to 10 μΐ, preferably 6.73 μΐ, of concentrated hydrochloric acid 2 μΐ to 10 μΐ, preferably 4 μΐ to 8 μΐ, of acetic acid.

In one embodiment of the invention, the elution vial contains 0.25 ml to 3 ml, preferably 0.5 ml, of elution solution composed of 5 mol/1 sodium chloride and 5.5 mol/1 hydrochloric acid with 10 μΐ to 100 μΐ, preferably 25 μΐ, of 5.5 mol/1 hydrochloric acid per ml of 5 mol/1 sodium chloride. The SCX cartridge is preferably eluted with 0.5 ml of the NaCl/HCl elution solution.

According to a second aspect of the invention there is provided a method for preparing a radiopharmaceutical, comprising the steps: eluting of a 68Ge/6aGa generator using hydrochloric acid as an eluant for obtaining a generator eluate comprising 68Gallium, feeding the generator eluate through a cation exchange cartridge, which collects the 68Gallium, and separates the 68Gallium from the used eluent, eluting the collected eaGallium from the cation exchange cartridge using a solution comprising sodium chloride and hydrochloric acid, and feeding the resulting eluate, into an aqueous precursor mixture comprising at least a labeling precursor thereby forming a reaction solution requiring no subsequent purification, wherein the solution for eluting the collected 63Gallium from the cation exchange cartridge follows directly after the generator eluate is fed through the cation exchange cartridge, and wherein the entire method is devoid of using organic solvents .

In one embodiment, the method may be carried out by means of the kit of the invention.

Working examples of the invention are elucidated in more detail below with reference to drawings.

In these drawings: figure 1 shows a schematic view of a kit for producing a radiopharmaceutical, and figure 2 shows an arrangement for producing a radiopharmaceutical by means of the kit.

Parts corresponding to one another bear the same reference numerals in all the figures.

Figure 1 shows a schematic view of a kit 1 for producing a radiopharmaceutical. The kit 1 comprises: - a cation exchange cartridge 2, - a reaction vial 3 with a mixture comprising a labeling precursor and a buffer salt, - a solution vial 4 with a solvent, - an elution vial 5 with a sterile solution comprising sodium chloride NaCl and hydrochloric acid HC1.

The labeling precursor present in the reaction vial 3 is a DOTA- or NODAGA-conjugated peptide, more particularly DOTATOC or DOTATATE.

The mixture in the reaction vial 3 has been lyophilized.

The mixture in the reaction vial 3 optionally comprises ascorbic acid C6H8C>6 or another radical scavenger.

The solvent is preferably formed as an aqueous solution from acetic acid C2H4O2 and hydrochloric acid HC1.

As the buffer salt, ammonium acetate CH3COONH4 or sodium acetate C2H3NaC>2 is provided.

The cation exchange cartridge 2 may be preconditioned with hydrochloric acid HC1 and water H20, in particular with 1 ml of hydrochloric acid HC1 of concentration 5.5 mol/1 and 10 ml of water H20.

The reaction vial 3 contains: at most 1 mg, preferably 15 pg to 100 pg, of the conjugated peptide, 20 mg to 40 mg, preferably 27.6 mg, of buffer salt, more particularly sodium acetate C2H3Na02, at most 100 mg, preferably at most 5 mg, of L-ascorbic acid C6H806 .

The solution vial 4 contains: - ml to 10 ml, preferably 1 ml to 3 ml, of water H20 - 2 μΐ to 10 μΐ, preferably 6.73 μΐ, of concentrated hydrochloric acid HC1 - 2 μΐ to 10 μΐ, preferably 4 μΐ to 8 μΐ, of acetic acid C2H402.

The elution vial 5 contains an amount of 0.25 ml to 3 ml of elution solution composed of 5 mol/1 sodium chloride NaCl and 5.5 mol/1 hydrochloric acid HC1 with 10 μΐ to 100 μΐ, preferably 25 μΐ, of 5.5 mol/1 hydrochloric acid HC1 per ml of 5 mol/1 sodium chloride NaCl.

The kit 1 may additionally comprise a vial with a neutralizing buffer, more particularly a sodium phosphate buffer.

Figure 2 shows an arrangement for producing a radiopharmaceutical 8 by means of the kit 1. A 68Ge/68Ga generator 6 provides the 68gallium needed for labeling. The 68Ge/68Ga generator 6 is eluted using hydrochloric acid HC1, with a concentration of 0.1 mol/1, for example. In this way, 68gallium is eluted and is held on the cation exchange cartridge 2. The generator eluate is supplied to the cation exchange cartridge 2. The 0.1 mol/1 HC1 effluent, possibly with traces of the 68germanium mother nuclide, is collected separately in a waste collecting vessel 9, and disposed of in line with the statutory provisions. The lyophilized mixture in the reaction vial 3 is dissolved with the solvent from the solution vial 4. The cation exchange cartridge 2 is then eluted by means of the solution from the elution vial 5 into the reaction vial 3.

The reaction solution which is produced in the reaction vial 3 may optionally be heated at 90°C to 100°C, over a time of 5 minutes to 15 minutes, for example, more particularly seven minutes, in order to accelerate the reaction, in which the 68gallium joins with the labeling precursor to form the radiopharmaceutical 8, also called tracer. The reaction may also take place at room temperature, in which case it requires a correspondingly greater amount of time.

At the end of the reaction, a sterile phosphate buffer may be added.

The reaction product may optionally be filtered using a sterile filter 7.

The tracer thus produced can then be used as radiopharmaceutical 8.

LIST OF REFERENCE NUMERALS 1 Kit 2 Cation exchange cartridge 3 Reaction vial 4 Solution vial 5 Elution vial 6 68Ge/68Ga generator 7 Sterile filter 8 Radiopharmaceutical 9 Waste collecting vessel

Claims

CXjAXMS

1. A kit when used for preparing a radiopharmaceutical from a fiSGe/68Ga generator eluate, comprising: a cation exchange cartridge for holding the generator eluate, a reaction vial with a ligand-conjugated peptide, a solution vial with a solvent comprising an aqueous solution of acetic acid and hydrochloric acid, an elution vial with a solution comprising sodium chloride and hydrochloric acid, a buffer salt, and instructions to add the solution to the solution vial and to elute through the cartridge into the reaction vial,
2. The kit of claim 1, wherein the buffer salt is contained in the reaction vial or in the solution vial.
3. The kit of claim 1 or claim 2, wherein the content of the reaction vial is lyophilized.
4. The kit of any one of claims 1 to 3, wherein the reaction mixture comprises a stabilizer.
5. The kit of claim 4, wherein the stabilizer comprises ascorbic acid.
6. The kit of any one of claims 1 to 5, wherein the buffer salt is one of ammonium acetate and sodium acetate.
7. The kit of any one of claims 1 to 6, wherein the buffer components hydrochloric acid and acetic acid in the solvent are provided in such an amount that, taking into account the amount of buffer salt, the pH value of the contents of the reaction vial, the solvent of the solvent vial and the elution solution of the elution vial used for eluting the SCX cartridge is between 3 and 4.
8. The kit of any one of claims 1 to 7, wherein the ligand-conjugated peptide is selected from the group comprising DOTA-conjugated peptides, DOTATOC, NODAGA-conjugated peptides, and DOTATATE.
9. A method for preparing a radiopharmaceutical, comprising the steps: eluting of a 68Ge/68Ga generator using hydrochloric acid as an eluant for obtaining a generator eluate comprising 68Gallium, feeding the generator eluate through a cation exchange cartridge, which collects the 68Gallium, and separates the 6SGallium from the used eluent, eluting the collected S8Gallium from the cation exchange cartridge using a solution comprising sodium chloride and hydrochloric acid, and feeding the resulting eluate, into an aqueous precursor mixture comprising at least a ligand-conjugated peptide thereby forming a reaction solution, and wherein the solution for eluting the collected 68Gallium from the cation exchange cartridge follows directly after the generator eluate is fed through the cation exchange cartridge .
10. The method of claim 9, wherein a buffer solution at least comprising a buffer compound is used to adjust the pH value of the reaction solution between 3 and 4.
11. The method of claim 9 or claim 10, wherein the buffer solution comprises a buffer salt, acetic acid and hydrochloric acid.
12. The method of claim 9 or claim 10, wherein one of sodium acetate and ammonium acetate is used as the buffer salt.
13. The method of any one of claims 9 to 12, wherein the reaction mixture is prepared by mixing a lyophilized precursor mixture of the ligand-conjugated peptide and the buffer salt using a solvent.
14. The method of claim 13, wherein the solvent is an aqueous solution of the buffer components acetic acid and hydrochloric acid.
15. The method of any one of claims 9 to 14, wherein the precursor mixture comprises a stabilizer for preventing radiolytic degradation of the radiopharmaceutical.

15. The method of claim 15, wherein the stabilizer is ascorbic acid.
17. The method of any one of claims 9 to 16, wherein the cation exchange cartridge is silica gel based.
18. The method of any one of claims 9 to 17, wherein the reaction solution is heated to a temperature of 90 to 100 °C over a time period of 5 minutes to 15 minutes.
19. The method of claim 18, wherein the reaction solution is heated to a temperature of 90 to 100 °C over a time period of seven minutes.
20. The method of any one of claims 9 to 19, wherein the radiopharmaceutical is neutralised by adding a phosphate buffer.
21. The method of any one of claims 9 to 20, wherein the ligand-conjugated peptide is selected from the group comprising DOTA-conjugated peptides, DOTATOC, NODAGA-conjugated peptides and DOTATATE.